BillFitzmaurice.info

My son and I would like to build a sound system that can be transported on a cargo bike like this http://www.google.ch/imgres?sa=X&rlz=1C ... =0&ndsp=16
It needs to be able to :
- play program music while riding for street parades or critical mass events
- arrive at venue and have patrons power the performance, kinda like this http://rockthebike.com/store/pedal-powe ... eaker.html
So the system can play music :
- on the bike as it was travelling (with tops on lower rack near the axle, subs on the rack)
- tops on rack (about 30" off the ground), subs independant
- tops on stand (up to 60" off the ground), the stand is bolted to the bike
- or tops on the stand alone, separate from bike
It should be modular, so that it is possible to transport : 2-4 tops, 2-4 subs, mics, stands, lighting

I need advice on:
- light, efficient tops, I'm thinking a pair of Jack Lite 12s
- light efficient subs, I'm thinking a pair of Tuba 24
- self-powered by T or D amps, preferably.

I have:
- the bike
- a battery powered sound board from behringer
- it all needs to run off the power produced by the bicycle, max 36V, no wish to convert power.

I have hopes of my son's buddies getting bikes to transport different parts of a system (Stage, Lighting) and make a business of this.

I'd appreciate your help on this project.

I'll give a +1 to the Jack 12 Lites, but a -1 for the Tuba 24s. Your power requirements for a "portable" mixer will be difficult to meet. For an amp, use a mono 12 automotive amp, and run the J12Ls in parallel off that. I -1 the Tubas (any subs), in this case, as portability is the #1 factor, leaving no room for subs or a crossover.



As you can see by the chart above, there is not much to be gained by adding in T24s. Just not worth the time and expense, in this case.

How about a pair of truck tubas as panniers?

Ahh yes, portable sound
If you want to run it from the 36v bicycle battery, look at something from Sure Electronics - ie, TAS5630 chip amp
Personally I'd run the sound off seperate power to the bike, so you don't run the bike flat with music then have to pedal home at the end of the night. That would be no fun.
Car amps can be great for 12v systems but you have to be picky to get a good quality Class D amp that's efficient enough for portable battery-powered use. Alpine PDX gets heaps of praise, and I'm happy with my Pioneer GM-D which is a bit more affordable

What functions do you want from the mixer? You may get ground loops if the mixer is running from a seperate power supply (ie, internal batteries) than the amp
Also, for crossover I'd look at a MiniDSP 2x4, and that could be advantageous even if you're running full range boxes, just to have high pass and EQ available to extend battery life (cut unwanted bass) and tweak sound

As for the speakers... Jack12 is wide - 550cm, and you have no hope of fitting a BFM sub on the cargo bike alone. Trailer could be an option, but even then a horn loaded sub isn't ideal
Most portable systems lean towards reflex designs, for quite a few reasons. Not trying to talk down BFM designs, they're just not very appropriate for this specific application. You could fit 2x J12 on top of the cargo rack, or perhaps look at something like the Boominator design which you could split in half and mount either side of the racks

Key things to note, from my learnings:
best to start small and simple, then build from there - as you learn you'll find your intentions will change direction
making bass outdoors takes a lot of resources, big boxes and power - best to forget sub bass and just worry about 60-80hz and up
cone surface area matters - you don't have much space to work with, speakers make noise... plywood doesn't!

Just to give background to my advice, I started with a couple of small boxes and got carried away very quickly. Built a pair of tapped horn subs and mounted it on a 4 wheeled trolley with 100ah battery. It kicked arse, but was too big and heavy to move around. No point having a killer portable sound system, if the lack of portability is a killer
I've taken a step back, binned the subs and have plans for a new modular rig. OT12 tops will feature for bigger events but when it's mounted on the tricycle I want, I'll use smaller reflex boxes only... anyway, enough from me for now - I'm sure there are plenty of options and opinions to discuss...

Good to see the pedal power getting attention it deserves!

Hello, and welcome to the forum!

How about a pair of SLAPro? You could hang one on either side of the bike, which would leave room on the rack for other stuff. Add a couple of latches to make an 8 driver column. This allows you to throw the sound farther with clarity (than a JBL PRX ground mounted).

I know that bitSmasher does not recommend a sub, but, I was thinking of a wide Titan30 with tires mounted on so that it could be towed behind, trailer fashion.

After snooping around (because others have dropped hints on mobile), I noticed that for digital amps it would be better to get close to 30-36 volts for better sound reproduction.

i'd say a wide t39 would serve as a better "trailer sub". it doesnt matter if its pointing upwards lol.

DJPhatman wrote: As you can see by the chart above, there is not much to be gained by adding in T24s. Just not worth the time and expense, in this case.

True, there doesn't seem to be much of an advantage to the T24s in low end. I imagined coupling them and hoping for something to bounce them off.

Tom Smit wrote:Hello, and welcome to the forum!

How about a pair of SLAPro? You could hang one on either side of the bike, which would leave room on the rack for other stuff. Add a couple of latches to make an 8 driver column. This allows you to throw the sound farther with clarity (than a JBL PRX ground mounted).

I like the idea, but it seems that I'd have to get Neo drivers to keep the weight down, and that would drive the price way up

Tom Smit wrote:I know that bitSmasher does not recommend a sub, but, I was thinking of a wide Titan30 with tires mounted on so that it could be towed behind, trailer fashion.

Great idea making the sub a trailer. As Sine143 pointed out, the dimensions of the T39 seem even better suited, and with outboard wheels, and connection to the rack directly, that would be a slick system.

Tom Smit wrote:How about a pair of SLAPro?

+1

A single SLAPro. No subs. That will get you "flat to 100Hz" in a single 30-35 pound package. That is about the best SPL/pound your are likely to get.

If you insist on a sub, build a T39, anything between about 20-24" - whatever works best with the bike. Put it "downward firing," add wheels, and pull it like a trailer. Given the limited power, even the BP102 driver would not max out...but the 3012LF would be handy for cases where you had "ground power."

Outboard wheels on a T39 = WIN! +100

One (obvious) thing I have found whilst building is that some plywood is lighter than others. I got some really bad ply that had the veneer on - it was a proper PITA to make the sub BUT once all the swearing at the wood had subsided I realized that my creation was so light!! (ok, not light, but light in comparison to my other cabs) The lightness does mean that the sub dings up a little easier than a BB cab.
I *think* Auraco is the lightest recommended wood

If I'm right , I'd go with that to make transportation easier.

It's also nice to see that more people are coming out as bike-curious.

SoundInMotionDJ wrote:. Put it "downward firing," add wheels, and pull it like a trailer.

I think we will wait on the sub, but when we do, I think I can make the T39 30" wide, so it's more stable on outboard wheels as suggested. Then I can connect it with this hitch.
http://www.andersen-shopper.de/en/produ ... aengt.html
Down-facing that thing should really put out some sound. It'll be a nice addition.

I'd consider loading the t39 with the 4 ohm lab 12, to extract the most out of your amp.

bitSmasher wrote:Ahh yes, portable sound If you want to run it from the 36v bicycle battery, look at something from Sure Electronics - ie, TAS5630 chip amp

I guess the first decision is, which voltage and charging system. What I imagined was the bionx system which I can get at dealer price that charges when braking so at the venue, the brake would be held on with a strap and the rear wheel raised to allow pedalling. The electric-assist bike system I'm looking at can be 36 or 48V and store 8.8A/h per battery. http://www.bionxinternational.com/en/ If I use this system, the amps suggested look like the ticket.

bitSmasher wrote:Personally I'd run the sound off seperate power to the bike, so you don't run the bike flat with music then have to pedal home at the end of the night. That would be no fun.

I've used this cargo bike, without electric assist, to move house several times (fridge, stove, lotsa boxes) and it surprisingly easy to move lots of gear, albeit slowly and surely. The only load I had trouble with was 2, 4-drawer old steel filing cabinets, but I tried to start out on a slight uphill incline. Once I got going, it's fine. So it's not much of a problem if the battery is almost drained after a gig.

bitSmasher wrote:Car amps can be great for 12v systems but you have to be picky to get a good quality Class D amp that's efficient enough for portable battery-powered use. Alpine PDX gets heaps of praise, and I'm happy with my Pioneer GM-D which is a bit more affordable

The PDX is even a 4 channel + 1, so that could power the whole system. Nice.

bitSmasher wrote:What functions do you want from the mixer? You may get ground loops if the mixer is running from a seperate power supply (ie, internal batteries) than the amp
Also, for crossover I'd look at a MiniDSP 2x4, and that could be advantageous even if you're running full range boxes, just to have high pass and EQ available to extend battery life (cut unwanted bass) and tweak sound

I'd like 8 channels in, L/R & Sub out, FX and monitor send. the behringer has that, I'll test out the ground loops. Thanks for the tip on the dsp, that will have to be an essential part of the system.

bitSmasher wrote:As for the speakers... Jack12 is wide - 550cm, and you have no hope of fitting a BFM sub on the cargo bike alone. Trailer could be an option, but even then a horn loaded sub isn't ideal

The space on the lower racks is bigger than one thinks, the speaker can be up to 36" wide and 17"-24" tall (which would still keep the top rack space free for stands, etc.). The only limit on depth, is trying to keep it down to a maneuverable width in traffic, so under 30".

bitSmasher wrote:Most portable systems lean towards reflex designs, for quite a few reasons. Not trying to talk down BFM designs, they're just not very appropriate for this specific application. You could fit 2x J12 on top of the cargo rack, or perhaps look at something like the Boominator design which you could split in half and mount either side of the racks

We are considering a Keep It Super Simple system with a pair of 12" B&C 12CXT coax that I have, in a reflex cab

bitSmasher wrote:Key things to note, from my learnings:
best to start small and simple, then build from there - as you learn you'll find your intentions will change direction
making bass outdoors takes a lot of resources, big boxes and power - best to forget sub bass and just worry about 60-80hz and up
cone surface area matters - you don't have much space to work with, speakers make noise... plywood doesn't!

All precious advice which will be taken into account as the project moves forward.

bitSmasher wrote:I've taken a step back, binned the subs and have plans for a new modular rig. OT12 tops will feature for bigger events but when it's mounted on the tricycle I want

If I can make a suggestion the Yuba Mundo is surprisingly stable, carries over 300lbs and is reasonably priced. Trikes are usually very heavy, not very maneuverable, and expensive. My 2c.

Thanks for all the great advice.
takeC@re,
Tim

sine143 wrote:I'd consider loading the t39 with the 4 ohm lab 12, to extract the most out of your amp.

Again more precious advice.. the sensitivity doesn't seem that high though "89.2 dB 1W/1m" and the literature says 6 ohm http://www.parts-express.com/eminence-l ... r--290-570
If I've understood correctly, the recommendation comes because this is a very dependable, high-power driver that is efficient thanks to the horn-loaded design.

Try this link for the Lab 12C (the 4 ohm version) http://www.parts-express.com/eminence-l ... m--290-668

The manufacturers sensitivity is rated in an infinite baffle enclosure, look at the forum heading "SPL charts" for the sensitivity in Bill's horns.